Video: Volcanic Hazards & Prevention: Landslides, Lahars & Tsunamis

Volcanic hazards are any volcanic process that can damage property or threaten life. Learn about volcanic hazards, such as landslides that can trigger lahars and tsunamis, and ways to prevent these hazards from threatening people's lives.2013-11-21

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

Volcanic hazards are any volcanic process that can damage property or threaten life. Learn about volcanic hazards, such as landslides that can trigger lahars and tsunamis, and ways to prevent these hazards from threatening people's lives.

Volcanoes

Volcanoes can erupt with so much force that they eject small particles up into the stratosphere. Their destructive power can cause the area around the volcano to become uninhabitable, and even trigger ocean waves so large they can travel across entire oceans and destroy coastal areas thousands of miles away. In this lesson, you will learn about volcanic hazards that cause damage both at the site of the volcanic eruption and miles away, and get some insights into ways to prevent these hazards from harming people.

Volcanic Hazards: Landslides and Earthquakes

A volcanic hazard is any volcanic process that threatens life or destroys land or infrastructure. When you think of a volcanic eruption, you may get a picture in your head of red-hot lava rushing down the slope of a volcano, and while this is perhaps the most remarkable feature of a volcano, lava is not the only hazardous material to fall from a volcano.

A landslide is a mass movement of rock fragments, soil and debris downslope. Landslides can happen at any mountain where the slope of the mountain has become less stable, but they are commonly associated with volcanic activity because the volcanic mountain is weakened by the magma and pressure brewing inside. For example, magma can get injected into volcanic rock and the sides of the volcano as it rises toward the surface. This can weaken the slopes of the volcano, leading to a landslide.

It can also lead to a volcanic earthquake, which is an earthquake induced by the pressure and stress of volcanic activity. Volcanic earthquakes can then trigger landslides.

Lahars

Landslides create a number of hazards to people and property because they have a potential to travel long distances, and they pick up momentum and speed as they travel down the slope of a volcano, with the ability to travel at more than 50 miles per hour. The debris that's carried in a landslide destroys anything in its path, buries valleys in rock and debris and can dam waterways, leading to flooding.

If the debris within the landslide mixes with enough water, the landslide can turn into a lahar and continue to travel for miles. A lahar can be defined as a flowing mass of volcanic debris and water. A lahar resembles a river of wet cement flowing down a volcano and into a valley.

They vary in speed depending on the amount of water and the size of the debris being carried in the flow. The wettest lahars travel tens of meters per second, making them impossible to outrun. Therefore, lahars are extremely dangerous and destructive for communities living downslope of a volcano.

Some communities have built structures around their living areas to act as barriers to the flow of lahars and prevent destruction. However, the best preventative measures are to be prepared with evacuation routes for citizens of the communities and the development of a warning system that can detect if conditions are wet enough to support a lahar or to detect seismic signals of a lahar barreling down the valley.

Tsunamis

Another volcanic hazard that can be triggered by a landslide is a tsunami. A tsunami is a series of large ocean waves caused by an abrupt disturbance, such as a landslide. A tsunami travels quickly in deep ocean waters, reaching speeds of more than 500 miles per hour, which means it could outrace a jet plane.

As a tsunami reaches a coastline, the shallow waters slow it down but cause it to build in height. A tsunami can grow to over 100 feet high and travel far inland, engulfing anything in its path. There is little that can be done to prevent a landslide and a subsequent tsunami, so the focus is on how to prevent the loss of life. Educating those living in an area near volcanoes or in tsunami-prone areas can help people prepare for evacuation. Progress has also been made in the establishment of tsunami warning systems, which are possible due to technology that can detect the unique wave frequency of a tsunami.

Lesson Summary

Let's review. A volcanic hazard is any volcanic process that threatens life or destroys land or infrastructure. A landslide is a mass movement of rock fragments, soil and debris downslope. They are commonly associated with volcanic activity because the volcanic mountain is weakened by the magma and pressure brewing inside. This can weaken the slopes of the volcano, leading to a landslide, or cause a volcanic earthquake, which is an earthquake induced by the pressure and stress of volcanic activity. Volcanic earthquakes can then trigger landslides.

The debris that is carried in a landslide destroys anything in its path, buries valleys in rock and debris and can dam waterways, leading to flooding. If the debris within the landslide mixes with enough water, the landslide can turn into a lahar, which is a flowing mass of volcanic debris and water. Barriers can be built to block the flow of lahars. However, the best preventative measures are to evacuate people and the development of a warning system.

Another volcanic hazard that can be triggered by a landslide is a tsunami, which is a series of large ocean waves caused by an abrupt disturbance, such as a landslide. A tsunami can grow to over 100 feet high and travel far inland, engulfing everything in its path. Prevention of injury includes educating people and helping them prepare for evacuation, as well as the establishment of tsunami warning systems.

Learning Outcomes

You might have the ability to do the following after reviewing this lesson:

Give the meanings of volcanic hazard and landslide

Tell what happens during a lahar and a tsunami

Indicate what can be done to detect a lahar or tsunami and prevent loss of life during such occurrences

Summary:

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